Liquid diglycerides have been found to have effects such as decreasing the accumulation of body fats and preventing obesity (JP-A10-176181 or JP-A4-300826). Also, liquid diglycerides are known to have characteristics of enhancing a milky taste and full-body taste when used in coffee cream compositions containing an oil-in-water type emulsion (JP-A 3-8431). From this point of view, fat or oil compositions having a high liquid diglyceride content are used as domestic edible oils.
There is a desire to use such liquid diglycerides having a health benefit in broader applications. For example, utilization of fat or oil in ice cream coating composition is known (JP-A 9-510622). In general, fat or oil (triglycerides) having saturated fatty acids and trans acids in a high content are used as foaming fat or oil applicable to frozen sweets and the like. There are technologies (JP-A 7-313066, JP-A 8-103236 or JP-A 2002-10738) using diglycerides having a high content of a specific saturated fatty acid when using diglycerides and technologies ensuring good foaming characteristics and foam shape-keeping ability by a combination of a liquid diglyceride having a low saturated fatty acid content and a hydrogenated oil (JP-A 63-301765). Also, water-in-oil type frozen sweets using liquid diglycerides are disclosed (JP-A 64-63341).
In the meantime, hydrogenated oils which are widely used as foaming fat or oil have not only a high saturated fatty acid content but also a high trans acid content. As typical trans acids, elaidic acid is known and a method of applying the foaming characteristics and foam shape-keeping ability thereof to an ice cream is known (JP-A 53-32164). However, studies have been recently made as to the influence of saturated acids and trans acids on health and there are some trends toward limiting its intake (Alice, H. Lichtenstein, et al., EFFECT OF DIFFERENT FORMS OF DIETARY HYDROGENATED FATS ON SERUM LIPOPROTEIN CHOLESTEROL LEVELS, “The New England Journal of Medicine”, USA, the Massachusetts Medical Society, vol. 340, No. 25, pages 1933 to 1940 (1999))